Field
The present invention relates to a medical or dental hand instrument, in which the tool-holding device can be induced to a stroke movement.
Description of Prior Art
Patent Application WO 2013/076106 A2 discloses a medical, in particular dental, hand instrument, in which the tool-holding device can be induced to a simultaneous stroke and rotational movement. To transfer the rotational movement to the tool-holding device, a hollow shaft is provided, wherein on one end of the hollow shaft a gearwheel is disposed which engages another gearwheel on the tool-holding device. For generating the stroke movement an eccentric gear is provided having an eccentric pin and a recess that accommodates the eccentric pin on the tool-holding device. The eccentric pin is disposed on a second shaft, which is supported in the hollow shaft with the gearwheel. A stepdown gear is additionally provided for reducing the rotational speed of the hollow shaft and thus the tool-holding device as well, so that the rotational speed of the tool-holding device is reduced with respect to the stroke frequency.